Rich-Gas Absorption-Stabilization With Stepwise Compression
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Solution Overview
Problem
Existing petroleum refining processes face challenges in efficiently utilizing rich gas and crude gasoline from catalytic cracking units, leading to high energy consumption and insufficient production of high-value chemical products like propylene, while the construction of PDH units is constrained by propane raw material limitations.
Innovation Solution
A novel absorption-stabilization process involving stepwise compression, absorption, and cracking operations using molecular sieves in fixed and fluidized bed reactors, followed by selective separation and reforming, to maximize the production of high-value chemicals like propylene and butene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional absorption-stabilization processes are used to separate rich gas and crude gasoline, then the basic separation function is achieved, but energy consumption is high and production of high-value chemical products is insufficient
Solution Approach 1:
The process segments the rich gas treatment into multiple stages: primary compression to 0.6±0.2MPa for de-heavy tower separation, followed by secondary compression of C3-rich gas to 1.4±0.3MPa. This segmentation allows optimized energy input at different pressure levels rather than single high-pressure compression, reducing overall energy consumption while enabling comprehensive product utilization.
Solution Approach 2:
The absorption-stabilization unit is enhanced with multi-functionality by integrating it with downstream chemical conversion processes. The stabilized gasoline and liquefied gas are fed to fluidized bed reactors for cracking to produce propylene and other high-value chemicals, making the system not only separative but also productive of valuable chemical feedstocks.
2Productivity
If PDH units are constructed to increase propylene production, then propylene supply is improved, but propane raw material constraints and technology risks increase
Solution Approach 1:
The system achieves self-service by producing its own propylene feedstock from the absorption-stabilization process outputs. The stabilized gasoline and liquefied gas containing C3-C4 components are cracked in fluidized bed reactors to generate propylene, eliminating dependence on external propane supplies and PDH unit technology.
Solution Approach 2:
The process changes the chemical parameters of the feedstock by cracking heavier hydrocarbons (C4+) into lighter olefins including propylene. This parameter transformation converts the limitation of propane availability into an advantage by generating propylene in-situ from the catalytic cracking unit outputs.
3Manufacturing precision
If rich gas is compressed to high pressure for efficient separation, then separation efficiency is improved, but energy consumption increases
Solution Approach 1:
Compression is segmented into two stages with intermediate separation: first compression to 0.6±0.2MPa for de-heavy tower operation, then second compression of the C3-rich overhead to 1.4±0.3MPa for absorption tower feeding. This avoids the high energy cost of single-stage high-pressure compression while achieving the necessary separation precision at each stage.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Significantly reduces energy consumption by up to 40% and enhances the production of high-value chemical products, such as propylene and butene, through optimized utilization of rich gas and crude gasoline.
Implementation Method 1
compressing the rich gas from a catalytic fractionation unit using a first compressor to a pressure of 0.6±0.2MPa
Implementation Method 2
the compressed rich gas is directly fed into a de-heavy tower for separation by rectification
Implementation Method 3
condensing the overhead fraction of de-heavy tower and subjected it to a gas-liquid separation inside a first reflux tank
Implementation Method 4
introducing the gas phase mainly containing C 3 from the top of the first reflux tank to an inlet of a second compressor, where it is compressed to 1.4±0.3MPa
Implementation Method 5
after the secondary compression, the gas phase is condensed and subjected to a gas-liquid separation inside a second reflux tank
Implementation Method 6
the crude gasoline absorbs C 3 and C 4 components from the gas phase materials to form a rich-absorption oil
Implementation Method 7
feeding materials from the bottom of the de-heavy tower and the rich-absorption oil from the bottom of the absorption tower respectively into a stabilization tower, wherein a liquefied gas fraction is drawn off from the top of the stabilization tower, and a gasoline fraction is drawn off from the bottom of stabilization tower
Implementation Method 8
A novel absorption-stabilization process involving stepwise compression, absorption, and cracking operations using molecular sieves in fixed and fluidized bed reactors
Data Source
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AI summary
The present invention relates to a novel process of an absorption and stabilization unit, comprising operation steps of: S1, primary compression of rich gas, S2, secondary compression of rich gas, S3, dry gas absorption, S4, gasoline stabilization, and so on. After rich gas from a catalytic fractionation unit undergoes operations such as primary compression, rectification using a de-heavy fractionator, and secondary compression, the gas phase mainly composed of C3 from the top of the de-heavy fractionator and naphtha from the catalytic fractionation unit are absorbed in an absorption tower, and dry gas of unabsorbed components is discharged from the top of the absorption tower; rich-absorption oil from the bottom of the absorption tower and the liquid phase mainly composed of C4 from the bottom of the de-heavy fractionator enter an stabilization tower to perform stable operation. The novel process of the absorption and stabilization unit of the present invention can obviously reduce the energy consumed by the absorption and stabilization unit by means of step-by-step compression, and facilitates further utilization of products from the absorption and stabilization unit. The present invention also relates to a method for comprehensive utilization of products from the absorption and stabilization unit, for maximizing the conversion of effective components in stabilized gasoline, liquefied gas, and dry gas after the novel absorption and stabilization process into high value-added chemical products such as propylene.